In certain types of surgical procedures, the use of surgical staples has become the preferred method of joining tissue and, as such, specially configured surgical staplers have been developed for these applications. For example, intra-luminal or circular staplers have been developed for use in surgical procedures involving the lower colon wherein sections of the lower colon are joined together after a diseased portion has been excised. Circular staplers useful for performing such procedures are disclosed, for example, in U.S. Pat. Nos. 5,104,025; 5,205,459; 5,285,945; and 5,309,927 which are each herein incorporated by reference in their respective entireties.
In general, a conventional circular stapler typically consists of an elongated shaft that has a proximal actuating mechanism and a distal stapling mechanism mounted to the elongated shaft. The distal stapling mechanism commonly consists of a fixed stapling cartridge that contains a plurality of staples configured in a concentric circular array. A round cutting knife is concentrically mounted in the cartridge interior to the staples for axial travel therein. Extending axially from the center of the cartridge is a movable trocar shaft that is adapted to have a staple anvil removably coupled thereto. The anvil is configured to form the ends of the staples as they are driven into it. The distance between a distal face of the staple cartridge and the staple anvil is commonly controlled by an adjustment mechanism that is mounted to the proximal end of the stapler shaft for controlling the axial movement of the trocar. Tissue that is clamped between the staple cartridge and the staple anvil is simultaneously stapled and cut when the actuating mechanism is activated by the surgeon.
When performing a lower colon procedure using a circular stapler, the intestine is typically stapled using a conventional surgical stapler with double rows of staples being emplaced on either side of the diseased portion of intestine to be removed. The target section is simultaneously cut as the adjoining end is stapled. After removing the diseased portion, the surgeon typically inserts the anvil into the proximal end of the lumen, proximal of the staple line. This is done by inserting the anvil head into an entry port cut into the proximal lumen by the surgeon. On occasion, the anvil can be placed transanally, by placing the anvil head on the distal end of the stapler and inserting the instrument through the rectum. The surgeon then ties the proximal end of the intestine to the anvil shaft using a suture or other conventional tying device. Next, the surgeon cuts excess tissue adjacent to the tie and the surgeon attaches the anvil to the trocar shaft of the stapler. The surgeon then closes the gap between the anvil and cartridge, thereby clamping the proximal and distal ends of the intestine in the gap. The surgeon next actuates the stapler causing several rows of staples to be driven through both ends of the intestine and formed, thereby joining the ends and forming a tubular pathway. Simultaneously, as the staples are driven and formed, the concentric circular knife blade is driven through the intestinal tissue ends, cutting the ends adjacent to the inner row of staples. The surgeon then withdraws the stapler from the intestine and the procedure is complete.
During such lower colon procedures, it may be difficult to insert the surgical stapler thru the anus and past the transverse folds in the rectal wall that protrude into the colon which are commonly referred to as the “Valves of Houston” and subsequently manipulated to the desired area. This problem is exacerbated when the stapler must be inserted without the anvil in position. In particular, the forward or distal end of most circular staplers comprises a relatively abrupt circular-shaped member designed to support a circular staple cartridge. Such blunt/abrupt shape makes it difficult to advance the forward end of the stapler past the Valves of Houston and other tissue.
Thus, the need exists for devices and methods for easily inserting a surgical stapler through a patient's anus into the lower colon or into other areas within the patient.
The foregoing discussion is intended only to illustrate some of the shortcomings present in the field of the invention at the time, and should not be taken as a disavowal of claim scope.